Enhancement of optical, mechanical and micro structural properties in nanocomposite films of PVA doped with WO3 nanoparticles

Abstract

Purpose – The purpose of this paper is to explore the synthesis, preparation and investigation of micro structural, optical and mechanical studies of polyvinyl alcohol (PVA) doped with tungsten oxide (WO3) nanocomposites films. These films were prepared by simple solvent casting method is further characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-visible spectroscopy, universal testing machine (UTM), scanning electron microscope (SEM), energy-dispersive analysis of X-rays (EDAX) and atomic force microscope (AFM) techniques to determine the enhancement in structural, optical and mechanical properties with increase in dopant concentration. Design/methodology/approach – The present paper deals with the synthesis of WO3 nanoparticles using precipitation method and doping into PVA matrix to prepare a polymer nanocomposite film using coagulation and solvent casting method. The FTIR explores the interaction of dopants with PVA matrix. The XRD spectra investigate the variation of crystallinity. The UV/Vis-spectra reveals the information of optical energy band gap and the Urbach Energy for different doping concentrations. The mechanical properties of the nanocomposites were exposed using UTM. The phase homogeneity, film topography, chemical composition of nanocomposites is analyzed using SEM, EDAX and AFM techniques supporting the above results. Findings – The films characterized by FTIR spectroscopy explores the irregular shift in the bands of pure and doped PVA can be understood on the basis of intra/inter molecular hydrogen bonding with the adjacent OH group of PVA backbone. The XRD result reconnoiters that the particle size and crystallinity increases whereas microstructural strain and dislocation density decreases with increase in dopant concentration. Further the drastic decrease in optical energy band gap E g =0.94 eV for doping concentration x=15 wt% and the increase in values of Urbach Energy (E u ) with doping concentrations were investigated by UV/Vis spectra. Also the extinction coefficient was high in the wavelength range of 250-400 nm and low in the wavelength range of 400-1,200 nm. The mechanical studies indicates that the addition of the WO3 with weight percentage concentration x=15 percent increases the tensile strength and Young’s modulus. The phase homogeneity, the particle size of the dopants and chemical composition of nanocomposites is analyzed using SEM and EDAX. The film topography of the nanocomposites is analyzed using AFM techniques supporting the above results. Originality/value – The investigation of synthesis, preparation and investigation of micro structural, optical and mechanical studies of PVA doped with WO3 nanocomposites films as been done. The results prove that these nanocomposites having good mechanical strength with crystalline nature and also very low optical energy gap value that could find possible applications in industries.